A charged particle having charge q and mass m accelerated by a potential difference $V_0$ enters inside a parallel plate capacitor (parallel to length l of plates) at midpoint of its separation between plates at $t=0$. Potential difference across capacitor varies with time t as, $V=a d t$, where a is constant and d is separation between plates.
Angle of deviation as it comes out of plates, is $\frac{\pi }{4}$.
Value of $\frac{m{a}^2{l}^4}{2q{V}_0^3}$, will be